Electrically heated air fresheners are used for deodorizing and scenting the ambient air in an enclosed space such as in a home or office. These devices utilize a fragrance element that is heated to motivate the escape of a scent into the surrounding atmosphere. This is accomplished by increasing the temperature of the concentrated scenting material to heat scent molecules to a vapor pressure sufficient to escape the concentrated form and dissipate into the ambient air in a relatively high concentration.
Among the prior art devices used for this purpose, is a type using a plastic enclosure with male terminals that can be plugged into a wall outlet. An on/off switch may be provided as well as an LED to indicate the on or off condition. The plastic enclosure may be opened from the top to expose a cavity designed specifically to receive a fragrance block comprising scenting material. The fragrance block is preferably not visible when the top is closed. The floor of the cavity is, for example, a chromed metal plate that is heated by a ceramic body resistor that contacts the underside of the plate. A thermal transfer grease is placed between the ceramic body resistor and the metal heat transfer plate and held into position by a leaf spring. The resistor heats the plate which in turn, heats the fragrance block resting thereon. The plastic enclosure may be provided with adjustable louvers on the top and bottom so that the user may control the rate at which the fragrance is released into the ambient air. Also, the metal plate is preferably provided with side relief or edge openings to allow the air to flow past the plate and around the fragrance block. The above type of prior art device utilizes a conventional phenolic printed circuit board mounted in the fragrance housing separate from the heat transfer plate and the heating device.
Another type of prior art air freshener device is shown in U.S. Pat. No. 4,849,606. In this air freshener device, the fragrance block is supported in a cage-type holder that is sufficiently open that the block is visible to persons in the vicinity. The heating element in this device is a nichrome wire wound around a fiberglass core. This heating element is positioned within a molded plastic base which in turn is connected to electrical contact prongs or male terminals so that the device may be plugged into a standard wall receptacle. The electrical contact prongs are supported by the molded plastic base.
The prior art air fresheners such as those described above are of somewhat fragile construction and are vulnerable to damage and failure due to the rough treatment that typically may occur during use. Further, the electrical heating portions of such air freshener devices generally comprise multiple pieces or parts.
The air freshener of the present invention reduces the number of parts needed to form the electrical heating portion of the air freshener, facilitates miniaturization, provides an air freshener device that can withstand rough handling and affords other features and advantages heretofore not obtainable.